Field
Example aspects described herein relate generally to routing data on a network, and, more specifically, to rerouting network traffic based on capabilities of network elements involved in the rerouting of that traffic.
Related Art
Optical networks contain various network elements that are capable of sending and transmitting data, thereby allowing for communications on the network (referred to herein as “network traffic”). Network elements on an optical network can include components such as, for example, switch nodes, edge nodes, transport systems, network managers, and optical network terminals. These network elements can be communicatively coupled to each other, such that each network element is coupled to at least one other network element. Network traffic can be distributed among the network elements in various ways, with main hubs of network traffic being referred to as “nodes,” and the coupling between nodes being referred to as “links” or “legs.”
Typically, communications on an optical network are enabled by the “control planes” and “data planes” of the network elements. The control plane (CP) has the architectures and protocols used to define network topologies (e.g., sets of links between the network elements of the optical network) and facilitate data transmission (e.g., signaling, routing, network and addressing) and traffic engineering. Examples of control planes include time-division multiplexing (TDM) control planes and Internet Protocol (IP) control planes. The data plane, also referred to as the “forwarding plane” or “transport plane,” contains the architectures and protocols used to transfer data from one location on the network to another via the connections of network elements (e.g., links). Accordingly, network traffic can include information that is used by the control plane and information that is used by the data plane, for enabling the network elements to route and send the communications contained in the network traffic.
From time to time, interruptions in network service may occur, such that the capability to transfer data on one or more links of the network may be lost. Service interruptions, often referred to as “faults,” may occur when, for example, there is a problem in a link (e.g., a physical connection in a link may be disrupted, or a link may be overloaded with data). When there is a fault, network service may be restored by rerouting network connections to remove, avoid, or obviate the fault. Service restoration typically is guided by operations in the control plane. Specifically, during the rerouting process, the control plane can compute a new path in the network to avoid the fault based on existing network topologies. After computing a new path, the control plane performs re-signaling operations to reconfigure resources in the data plane to restore the network service(s).
Rerouting of network service may be initiated by a user (e.g., a network administrator), even in the absence of a fault. A user-initiated reroute may occur when, for example, a network administrator determines to disable or bypass a network link. A user-initiated reroute can be referred to as an “administratively-requested reroute,” or ARR. An ARR can be executed, for example, to reroute one specific CP call off of a network link, or to reroute all CP calls off of a network link, whether or not there is a fault on the link. The purpose of an ARR may be, for example, to isolate a network element from network service in order to perform maintenance, or to remove a network element from the network.
An ARR can impact the performance of the network because rerouting may introduce network traffic interruptions. For example, an ARR may cause one or more processes being performed by a particular network element to cease sending data to another network element, and begin sending the data to another network element. The network element, however, may not have the capability to switch paths without interrupting network service at that element in order to reconfigure at the data plane. In other words, the network element might be unable to perform hitless data plane operations to switch from a faulted path to a new path. Moreover, until the ARR is carried out, the user initiating it may not know whether the network elements involved have the hitless data plane operation capability necessary to switch connections without interrupting service. These issues are compounded when an ARR involves multiple network elements and links.
ARRs thus can impact network performance in way that affects a significant number of customers. This can make customers unhappy with the network performance and, in turn, unhappy with network administration. ARRs can further affect the network administration and customers because traffic-impacting events can be measuring factor or benchmark in service level agreements (SLA) that network customers have with the network carrier.